Gamma info not available

So I realize that I can go to the format of a clip and change the gamma within the item properties, I do it all the time, but this time it says nothing next to Gamma and I can't insert a value. Do you know why? I exported the footage as ProRes 422 from After Effects and imported it into Final Cut Pro, so I was hoping to switch the color space back to adobe so that it looks the same as I colored it in After Effects.